What is a Dedicated Outdoor Air System? | EnergyLink
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What is a Dedicated Outdoor Air System?

What is a Dedicated Outdoor Air System?

Before explaining what dedicated outdoor air systems are, we are going to talk about how indoor air quality affects our health. 

In order to save energy and keep the indoor environment comfortable, people have made many attempts. They started by creating a sealed building to limit the amount of infiltration and ventilation air to the minimum. Therefore, the warm air or cool air will be kept indoors without consuming too much energy.

However, this attempt was quickly proven ineffective due to a large increase in symptoms such as nose irritation, headaches, and dry coughs among occupants. Experts soon found out that the cause was the contamination in the air conditioning system.  

Since then, more and more studies have proven a correlation between indoor air quality and human illness. Hence, people have stopped sealing their buildings and started looking for a solution from the outside air. 

This brings us to the main topic of today– dedicated outdoor air systems.

How Does a Dedicated Outdoor Air System Work? 

If the term “dedicated outdoor air system (DOAS)” sound unfamiliar to you, no worries, we are here to explain it to you! 

From its name, we can guess that the system is used outdoors. However, it does not make sense to install a system to improve outdoor air quality. Thus, it is a system that is built outside and used to change indoor air. 

It is “an HVAC unit that is installed outside and is often used with other HVAC equipment,” according to the Refrigeration School. It acts as a filter for the HVAC system and helps it filter the outdoor air before the HVAC system brings it inside. In this way, the DOAS can remove the contaminants from outdoor air and reduce the chance of polluting the indoor air.

Dedicated Outdoor Air System (DOAS) Diagram

Normally, when the HVAC system is working, it tends to process more outdoor air before it can deliver cool or warm air inside. This is because the outside air is wet and will lower the efficiency of HVAC. However, a dedicated outdoor air system will dehumidify the outside air, reducing energy consumption during the process of ventilation. 

As a result, when paired with an indoor HVAC system, DOAS can further improve indoor air quality, reducing energy consumption and preventing moisture-related problems for the HVAC system.

Legal Standards for Outdoor Air

You may not be aware that there are actually legal standards in the United States for the amount of outdoor air which must be used inside buildings today. The exact amount of outdoor air required varies based on the size of the building, occupancy, and the state you live in. 

However, as a general rule, the EPA states that, if “outside air is provided through a mechanical system, then at least 15 cubic feet per minute (cfm) of outside air must be provided for each occupant.” So, in addition to aiding in improving indoor comfort, properly managing the use of outdoor air inside your facility will keep you in line with all legal standards.

If you are interested in increasing the energy efficiency of your air conditioning system and hope to improve the air quality to prevent your employers from falling asleep at work, a dedicated outdoor air system is for you. Click here to ask our experts any questions you have about DOAS!

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